UK T. (+44) 1492 582 323

Americas T. +1 (559) 456-1711

Asia T. (+852) 6503 3486

Gamma Spectroscopy

The natural gamma spectroscopy probe analyses the energy spectrum of gamma radiation from naturally occurring or man-made isotopes in the formation surrounding a borehole. The probe corrects for temperature drift is real-time by matching the acquired spectrum to base spectra of the main natural emitters, potassium, uranium and thorium determined during the tool master calibration. Available outputs are full-spectrum (static mode only) and continuous log measurements of elemental concentrations. Borehole corrections are available for casing thickness, borehole diameter, formation density and mud/fluid radioactivity for both centralized and side-walled tool positions.

Principle of Measurement:

Gamma photons produced by the decay of naturally occurring potassium, uranium, thorium and/or unstable man-made isotopes in the formation are detected by a large-volume gamma scintillation counter and converted to electrical pulses. The amplitude of the pulses depends on the photon energy. An analyzer within the probe separates the pulses into channels according to their amplitudes. Count-rates from groups of channels are converted in real-time by the surface software to concentrations of the originating elements using predetermined algorithms.


  • Large-volume scintillation detector for high sensitivity
  • Temperature compensation ensures freedom from drift


  • Uranium (ppm)
  • Thorium (ppm)
  • Potassium (%)
  • Gross gamma
  • Full spectrum display 100keV – 3MeV


Minerals / Water / Engineering

  • Shale/Clay typing
  • Correlation in complex situations
  • Mineral detection
  • Radioactive waste pollution measurement
  • Lithology determination


Diameter: 60mm
Weight: 6.5kg
Temperature: 0-70°C
Max. pressure 20MPa
Detector: Na(TI) scintillator
Detector Size: 38mm x 150mm
Energy range: 100keV to 3MeV

Operating Conditions

Borehole type: open/cased, water/air filled

Sales Information

I017478 Gamma Spectroscopy probe

Download Gamma Spectroscopy sheet


...Practical Innovation with Global Service & Support...

Robertson Geologging Ltd., 2017

how can we help you?

(+44) 1492 582 323